Location signaling device

ABSTRACT

A location signaling device comprising a wing balloon for signaling a location. The wing balloon is fixed to a tether line that itself is fixed to the location to be signaled. The wing balloon has an inflatable aerodynamically shaped hollow body to be at least partly be filled with a lighter-than-air gas and having a wing attack surface for air flowing relative to said wing balloon. The floating aloft of said wing balloon is supported by said air flow. When the wing balloon is inflated, a flexible wing portion is passively variable. The stronger the wind, the less attack is given. Thus, the dragging force on the tether line is generally static.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/587,160, filed Jun. 12, 2007, now U.S. Pat. No. 8,356,569 which is anational stage application of PCT/SE05/00087, filed Jan. 26, 2005, thedisclosure of which is hereby incorporated by reference.

FIELD

This invention pertains in general to the field of location signalingdevices, and more particularly to signaling devices for locating e.g.equipment or persons in emergency and/or in need of being located andpicked-up or rescued. Even more particularly, the invention relates to asignaling device rising above the location of a person in emergency orthe location of equipment, thus facilitating rescue or pick-pickoperations. The location signaling device is intended for use by e.g.persons in an emergency situation, for instance persons lost overboardof vessels, persons stranded with emergency landed airplanes, or personsinjured or lost in the wilderness, or equipment having e.g. finished atask and signaling its location for being picked-up.

BACKGROUND

One of the most difficult tasks of search and rescue (SAR) operationsare marine rescue operations at night times and heavy weather. Locatinga person swimming in the open ocean from larger distances is nearlyimpossible. Even when a rescue team, independently if situated on avessel or in an air-bound rescue vehicle, is very close to the swimmer,the swimmer itself is hard to discover. This is caused by obstacles suchas e.g. the ocean waves, rain, fog, and darkness. Ocean waves havemostly heights exceeding the height of the swimmer over the watersurface by multiple times. Land-based rescue operations, such as alpinerescue operations are another example of such difficult tasks.

Therefore, various types of signaling devices for signaling the positionof persons in an emergency or for locating equipment have been proposedin the past.

For instance a warning and signaling system including a kite attached toa flexible rope is disclosed in U.S. Pat. No. 4,768,739. The kite isused as an enhanced visibility warning and signaling device. The kite iscarried aloft by blowing wind. However, a kite 12 always needs at leasta certain amount of relative air movement, such as wind, in order tokeep the kite at a certain height. This is illustrated in FIGS. 1C and1D. To keep the signaling device at a minimum height is essential forthe efficiency of detecting persons in emergency. In situations of verycalm weather or windless weather conditions, a kite will drop to thesurface and not fulfill the signaling purpose. Moreover, a kite issensitive to turbulence and gets easily unstable, which leads to thekite crashing down on the surface. This is a basic disadvantage ofkites, limiting the range of use unnecessarily. Furthermore, for injuredor handicapped persons it is not possible to launch a kite.

Therefore location and signaling balloon devices have been proposed,e.g. in U.S. Pat. No. 4,944,242. A balloon body is in case of anemergency situation filled with a lighter-than-air gas from e.g. apressurized container or a chemical reaction. The inflated balloon isfixed to a tether line, which is e.g. attached to the person inemergency or to the ground near that person, in order to signal theposition of that person to search and rescue (SAR) operations. However,balloons have a number of disadvantages when being used as signalingdevices. Balloons are not suitable for use in windy weather conditionsin contrast to the above mentioned kites. With increasing wind velocitya balloon 1, fixed to a surface below by means of a tether line, will bedrawn down to the surface due to the resulting force F.sub.Ton theballoon being dominated by the dragging force F.sub.D of the wind on theballoon. This is illustrated in FIGS. 1A and 1B. The inclination angle.alpha. decreases from no wind (v.sub.w=0) with increasing windv.sub.w>0. One possibility to solve this problem is to increase the sizeof the balloon being filled with gas. However, this option is verylimited for the use in emergency signaling kits. This is due to the factthat these kits should be as compact and lightweight as possible whennot in use. This condition limits both the size of such a balloon andthe amount of available gas for inflating the balloon.

In order to overcome the drawbacks of signaling devices being based onpurely a kite or a balloon, it has been proposed to aerodynamicallyshape balloons in the form of a kite, e.g. in the patent applicationCA-A-2172852, or in the form of a wing, e.g. in U.S. Pat. No. 4,815,677.U.S. Pat. No. 3,657,752 discloses a locator device for locatingsubmerged equipment having returned to the surface of an ocean. Thedevice generates gas by a chemical reaction of a compound with water,whereupon the gas inflates a balloon-kite flying aloft tethered to acontainer at sea level. The balloon-kite is radar-detectable and ascendsinto the air above the water by means of the buoyancy of the gas-filledpart of the balloon-kite and/or the aerodynamic lift of the kite part ofthe balloon-kite. This is illustrated in FIGS. 1E and 1F. However, alsothese devices combining a kite or a wing with a balloon have certainundesired drawbacks. For example it is desired that a dragging forcethat is exerted by the signaling device on the tether line is generallyconstant at the point where it is fixed to a person in emergency, apiece of equipment, or a ground surface. The dragging force should beconstant within a certain limit. This ensures on the one-hand that theabove-mentioned dragging force of the signaling device does not exceed amaximum load of the tether line, thus preventing its rupture. A ruptureof the tether line which would render the signaling device useless asthe kite or the balloon flowing away will no longer signal the desiredlocation. In addition, a dragging force that comes close to orexceeds—the weight of the equipment or person, whose position is to besignalled, will result in an undesired effect of moving the person orequipment. This may be a health hazard for e.g. a person drawn throughthe water, causing the person to unintentionally get water into therespiratory system. Moreover, in case of e.g. a child or non-heavyequipment, the signaling balloon may draw the child or the equipmentover the ground, when used on land, resulting in injuries of the childor in damage of the equipment. In the worst case, the person orequipment will be raised out of the water or over ground. If thedragging force on the other hand becomes too low, the signaling devicewill not ascend sufficiently high and cannot fulfill its signalingpurpose.

A kite-balloon or a wing-balloon has the advantage that it remains aloftproperly under windless or low wind conditions due to the lifting forceof the lighter-than-air gas in the balloon. Moreover, at high windconditions, the aerodynamic shape of the kite or the wing compensatesfor the downward force imposed on the signaling device. At high windconditions, even these devices, notwithstanding the problem oftether-line-rupture, will become unstable due to turbulent behavior ofthe kite or wing as mentioned above.

Thus, there is a need for a new signaling device based on a combinationof a wing or kite with a balloon, avoiding the above-identified problemsand ensuring a generally constant dragging force on the tether line.

SUMMARY

The present invention overcomes the above-identified deficiencies in theart and solves at least the above-identified problems by providing alocation-signaling device, and a method according to the appended patentclaims.

The general solution according to the invention is to provide a wingballoon with a flexible wing portion. With increasing wind, the flexiblewing portion bends, and the effective surface of the wing is decreased.Thus, the lifting force generated by means of the wing is reduced andthe effect of increasing wind is compensated for. However, thesignalling wing balloon works also in no-wind weather conditions bymeans of the balloon being filled with a lighter-than-air gas liftingthe balloon. Bending of the wing is performed purely passively and noactive means or devices are necessary in the wing balloon to achieve thevariable attack surface. Thus, a very compact package design of thelocation-signaling device is achieved.

More particularly, the present invention has the advantage over theprior art that it provides an emergency signaling device being moreefficient than the known prior art devices. The signaling deviceaccording to the invention is usable over a wider range of weatherconditions than previously known devices. Furthermore, the deviceaccording to the invention provides a generally constant dragging forceon the tether-line, increasing safety of the device as well as comfortfor the users of the device. Hence, the present invention has theadvantage over the prior art that it is usable over a wide range of windconditions without unduly increasing the load on a tether line of alocation-signaling device.

Preferably, the wing balloon is easily visually detectable, thanks tothe fact that the wing balloon having a distinct color differing fromthe background. This color is e.g. a highly visible fluorescent orange.Optionally, several such colors are arranged on the surface of theballoon, for instance in stripes or other shapes, in order to generatean as high as possible visually detectable contrast.

In addition to that, the wing is formed such that a “waving” movementpattern of the balloon is achieved. For instance, the balloon flies onan elliptical path, or on a path in the form of a “8”. Thus, the visualdetectability of the wing balloon is further enhanced.

Optionally, the wing balloon is equipped with a smoke generating means.This means release smoke from the wing balloon, thus increasing thedistance of visibility.

Preferably, the wing balloon is fabricated from a material that reflectslight upon illumination.

Furthermore, the wing balloon is preferably made of a radar reflectivematerial or comprises radar reflective material or means, e.g. insidethe balloon as radar reflective swatches, or as radar reflective stripesor tails of e.g. aluminum attached to the rear of the wing balloon. Thisenables the wing balloon to be detected by radar, which allowsdirectional signal finding of the wing balloon providing its exactposition or direction in relation to a search vehicle. Radar detectionis given independently of the present weather conditions.

According to another preferred embodiment, the wing balloon is equippedwith a chemical heating means 122 (see FIG. 11). This providesdetectability of the wing balloon in 3D by means of thermocameras.

The wing balloon according to the invention increases drastically thesuccess rate of localization and rescue missions and improves thesurvival chances of persons in emergency.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features, and advantages of the invention will becomeapparent from the following description of exemplary embodiments of thepresent invention, reference being made to the accompanying drawings, inwhich:

FIGS. 1A to 1F are schematic illustrations of a pure kite, a pureballoon and a wing balloon in different windy weather conditions.

FIG. 2 is a schematic illustration of a location-signaling deviceaccording to an exemplary embodiment of the invention in thenon-inflated condition.

FIG. 3 is a schematic illustration showing the location signaling deviceof FIG. 2 with the wing balloon inflated and aloft.

FIGS. 4A to 4C are schematic illustrations showing the wing balloonaccording to different embodiments of the invention.

FIGS. 5 to 10 are photographic illustrations showing the wing balloonaccording to different embodiments of the invention.

FIG. 11 is a schematic illustration of an exemplary inflated wingballoon.

DETAILED DESCRIPTION

In an exemplary embodiment of the invention according to FIG. 2, alocation-signaling device 2 is shown in the non-inflated condition. Thedevice comprises a housing 20 and has approximately the size of a packetof cigarettes, although other designs, shapes, and sizes are possible,depending on the intended use as well as adherent conditions. The devicecomprises a fastening means 21, e.g. for fastening to an object such asa lifesaving jacket, a backpack, or other objects. The packet 2 containsan inflatable wing balloon 22. The wing balloon 22 is self-inflatingupon activation, wherein the gas originates from a gas storage device23, such as a gas cylinder containing compressed gas. The size of thegas cylinder is adapted to the size of the inflatable volume of the wingballoon. For instance, the gas cylinder has to have a size of 1/200 ofthe wing balloon inner volume at a compression pressure of 200 bar ofthe gas inside the gas cylinder. The gas for inflating the wing balloonis a lighter-than air gas, preferably non-inflammable or healthhazardous when inhaled, such as Helium. The inflation process isperformed in a non-explosive way, such that neither the balloon orpersons close to the device may be harmed or damaged. This improves aswell acceptance of the device by its users, in contrast to e.g. airbagsystems that inflate explosively. Preferably, a flow-limiting valve 24controls the inflation process, so that the inflation process takes acouple of seconds.

FIG. 3 shows the location signaling device of FIG. 2 with the wingballoon aloft thanks to the buoyancy of the wing balloon filled with theabove-described gas. The buoyancy principle is based on the fact that abody (=wing balloon) immersed in a fluid (=air) experiences a net upwardforce equal in magnitude to the weight of the fluid displaced by thebody. Here the lighter-than-air gas displaces the heavier air.

The wing balloon is fixed to a tether line 30 keeping the wing balloonat a fixed distance relative a fixed position 31. However, the heightabove the level of the fixed position 31 depends on prevailing windconditions and the resulting inclination angle .alpha. This heightinsures the detectability of the wing balloon and should not fall belowa certain limit. Therefore, the tether line has a sufficient length,e.g. ca. 10-40 m for marine rescue operations and ca. 50-100 m for landbased rescue operations, such as alpine rescue operations. Marine rescueor pick-up operations are often performed by using a helicopter. In thiscase, it is important that the line length is not too long, so that thewing balloon cannot get caught in the rotating helicopter blades. Asuitable length for the tether line is about 10 m in this case. Then thehelicopter is, after locating the location signaled by means of the wingballoon, able to hover over the location at a sufficiently low heightwithout risking incidents with rotor blades catching the tether line.Then the person or equipment in the water may be safely picked up bymeans of a lifting gear placed in the helicopter.

During land-based operations, the length of the tether line may bechosen longer, increasing the detection range of the wing balloon. Thisis due to the fact that e.g. a helicopter may land near the person orequipment to be picked-up, thus avoiding the helicopter blade relatedproblems.

In all cases, the length of the tether line is to be chosen, such thatthe detection range of the wing balloon is as far-reaching as possiblewithout causing other problems. The radar detection range of thelocation signaling device according to the invention is approximately40-50 km with the above-mentioned line lengths. The wing balloon ispreferably made of a signal reflecting material, wherein the range ofsignals reflected comprises light both visible and invisible as well asradar or radio waves. Preferably, the wing balloon is easily visuallydetectable at all weather conditions, thanks to the fact that the wingballoon having a distinct light reflecting color differing from thebackground. This color is e.g. a highly visible fluorescent color likeorange or yellow, or any other luminescent color including the range ofphosphorescent colors. Optionally, several such colors are arranged onthe surface of the balloon, for instance in stripes or other shapes, inorder to generate an as high as possible visually detectable contrast.

Furthermore, the wing balloon is preferably made of a radar reflectivematerial or comprises radar reflective material or means, e.g. insidethe balloon as radar reflective swatches, or as radar reflective stripesor tails 32 of e.g. aluminum attached to the rear of the wing balloon.This enables the wing balloon to be detected by radar, which allowsdirectional signal finding of the wing balloon providing its exactposition or direction in relation to a search vehicle. Radar detectionis given independently of the present weather conditions.

According to another preferred embodiment, the wing balloon is equippedwith a chemical heating means. This provides detectability of the wingballoon in 3D by means of thermocameras.

Hence, the wing balloon is designed to have maximum passivedetectability by means of visually and radar detectability.

Furthermore, the material of the wing balloon is preferablywater-repellent so that the weight of the wing balloon does not increaseby the weight of water soaked up in the material.

An Airfoil is generally a structure designed to create a reaction uponits surface from relative air movement relative to the structure. Thewing balloon is shaped as an airfoil having a variable reaction upon itssurface depending on the relative airflow velocity. More precisely, thewing has an effective ‘attack’ surface, which decreases with increasingairflow velocity. In this way, an increasing lifting force iscompensated for. The lifting force of the tethered wing balloon is theupward force resulting from the sum of aerodynamic lifting forces,dragging forces and buoyancy of the wing balloon. In contrast, thelifting force of an airplane is purely the upward force created by adifference in air pressure on both sides of an airfoil. Thus, by varyingthe ‘attack’ surface of the wing balloon, the amount of lift is changedarbitrarily and the lift generated is variable in a specific wayfavorable for keeping the dragging force on the tether line generallyconstant. Static and dynamic upward rising force is balanced againsteach other to ensure this effect. This is explained by the principle ofphysics that the wing balloon strives to an equilibrium in which the sumof all the forces on the wing balloon equals zero.

Air moving over and under the wing balloon, as the air is flowing pastthe wing balloon due to wind, creates this difference in air pressure.This is because the air that moves over the top of the wing has fartherto go because the wing is tilted slightly upward. The shape of the wingballoon is important for lift. A preferred shape is that the wingballoon has a curved, upper surface and a flatter, lower surface. Theair has further to go around on the top of the wing balloon, whereas thebottom of the wing balloon is generally flat, so air does not have asfar to go. Due to the shape of the wing balloon, the air on the bottomcan move faster to a certain point than the air on top. Difference ofmovement of air around the wing balloon creates this lift, and liftpushes the wing balloon against the downward force as explained above.However, at conditions with no relative air movement, the buoyancy isthe only lifting force. Hence, the resulting lifting force is balancedbetween the two lifting forces, namely buoyancy and aerodynamic liftingforce. This combines the advantages of both principles and ensures thatthe wing balloon is aloft over a wide range of wind conditions.

The wing balloon is designed that it becomes more and more arrow-shapedachieving the above-described dependency of the active wing surface onrelative airflow velocity. Due to inherent flexibility, the wing balloonwill revert to its original shape with decreasing relative airflowvelocity. Thus it is achieved, that the wing balloon generates agenerally static dragging force on the tether line in the range of 0-40m/sec airflow velocity.

In order to stabilize the wing balloon in the roll direction, the wingballoon is preferably equipped with stabilizing means such as tailsattached to the back of the wing balloon. These tails serve primarilythe aerodynamic purpose of stabilizing the wing balloon. Furthermore,these tails may be made of a radar-reflective material, such as aluminumstrips or tinfoil strips, so that they even fulfill the purpose ofradar/detectability.

It has to be pointed out that the wing balloon does not comprise anyactive control devices such as electronics, power sources such asbatteries, or active mechanical elements, such as wing surface varyingmeans known from e.g. supersonic airplanes.

The wing balloon is fixed to a tether line, e.g. a strong nylon threador string, having an appropriate length, in the range between 20 m and100 m, e.g. 30 m. The tether line itself is attached or fixed to afixpoint, such as an individual person, equipment, or a location. Thelifting force of the wing balloon is preferably designed such that atwind speeds of 33 m/sec the wing balloon does not turn down more than 45degrees from the vertical plane seen from the fixpoint.

In addition to the above-mentioned, the wing is preferably formed suchthat a “waving” movement pattern of the balloon is achieved at windspeeds above a certain lowest limit. For instance, the balloon flies onan elliptical path, or on a path in the form of a “8”. Thus, the visualdetectability of the wing balloon is further enhanced. A waving movementis easier to detect from a large distance.

Optionally, the wing balloon is equipped with a smoke generating means123 (see FIG. 11). This means release smoke from the wing balloon, thusincreasing the distance of visibility.

Preferably, the wing balloon is fabricated from a material that reflectslight upon illumination.

FIG. 4A to 4C are schematic illustrations showing the wing balloonaccording to different embodiments of the invention. FIG. 4A shows awing balloon 4 having a central inflatable body 41, side wings 42, 43and tails 51. With increasing relative air movement v.sub.w, the sidewings 42, 43 move in the direction of arrows 47, 44 and 45, 46respectively, i.e. in this case an upward inward movement decreasing theattack area of wing balloon 4 in relation to the relative air movementv.sub.w. FIG. 4B shows a wing balloon 5 having an arrow shapedinflatable body 48, side wings 49, 50 and tails 52 on each of the sidewing's ends. With increasing relative air movement v.sub.w, the sidewings 49, 50 move in the direction of arrows 55, 56, i.e. in this casean inward movement decreasing the attack area of wing balloon 5 inrelation to the relative air movement v.sub.w. FIG. 4C shows a wingballoon 6 in a side cross-sectional view. The wing balloon 6 has aninflatable body 58 and tails 53. With varying relative air movementv.sub.w, the rear portion of wing 6 moves in the direction of arrow 57respectively, i.e. in this case an inward movement decreasing the attackarea of wing balloon 4 in relation to increasing relative air movementv.sub.w and vice versa.

FIGS. 5 to 10 are photographic illustrations showing a variety ofdifferent exemplary wing balloons according to different embodiments ofthe invention, at least partly corresponding to FIGS. 4A to 4C.

FIG. 11 is a schematic illustration of an exemplary inflated wingballoon 110 having a tail 112, being tied to a tether line 111. Flexiblewing portions 113, 114 comprise adjacent inflated 113, 114 andnon-inflated chambers 115, 116, wherein said inflated chambers 113, 114and 119 respectively being connected to each other through conduits 120,121 in said non-inflated chambers 115, 116. Thus, the flexibility isachieved resulting in the resilient behavior of wings 113, 114 achievingthe variable attack surface of wing balloon 110.

A further way of achieving the resilient flexibility of a wing balloonis to vary the thickness of the wing balloon material appropriately. Athinner wall results in an easier to bend section of a wing and viceversa.

When during e.g. SAR operations a person in emergency has been locationthanks to the location signaling device of the invention, often the wingballoon is released by cutting off the tether line. This is most oftenperformed by the rescue person being dropped from e.g. a vessel or ahelicopter, then swimming to the person and taking care of the furtherpick-up proceeding. At this point the wing-balloon is released and fliesaway. In this condition the wing balloon may be a risk for air traffic,damaging airborne vehicles. In this case the wing balloon is optionallyequipped with a pressure release means, releasing the lighter-than-airgas from the inflated wing balloon. The pressure release valve ispassively activated by an increasing pressure in relation to thesurrounding pressure. The surrounding pressure decreases with increasingheight, approx. 1 mbar per 3 m. Alternatively this relative pressuredifference caused by the balloon rising, may cause the balloon toexplode. For instance, at a height of 450 m, the pressure difference is15 mbar. This pressure difference as a release pressure is sufficient toensure reliability of the location signaling device avoiding deflatingby mistake. After deflating or exploding, the residual elements are nolonger a potential danger for air-traffic. From an environmental pointof view the wing balloon may in this case be made from a bio-degradablematerial.

Applications and use of the above-described location-signaling deviceaccording to the invention are various and include exemplary fields suchas SAR operations of e.g. seamen, mountaineers, or skiers in need ofbeing rescued. Potential users of the device are persons, which may getinto life-threatening emergency situations at more or less remotelocations, at which the person's life depends on being detected andrescued by third persons. Such persons are e.g. the above-mentioned, butalso the rescuers themselves, i.e. SAR operators, pilots of airplanesand helicopters, rescue or life-saving service operators such as searescue or coastguard service operators. Another application is to havethe emergency kit integrated in life vests available on passenger boatsand other vessels, readily available in case of emergency, when alife-vest is put on by persons as a routine safeguard or duringemergency cases.

Another application is the location of equipment. One example of manypossible is to equip an oil sample-taking device that is dropped fromairborne vehicles into the sea where oil contamination has beendetected. The device takes oil samples from the surface for a lateranalysis in order to identify the cause or source of the contamination.Then the device has to be re/collected, whereby it is already adifficult task to locate the device due to the waves of the sea. Anotherproblem is to collect the device. Both problems may be solved by meansof the localization signaling device according to the present invention.A signaling wing balloon connected to the sampling device by means of atether line helps locating the sampling device. Furthermore, the tetherline may be constructed from such strong material, that it is possibleto collect the device by drawing it up from the sea with the tetherline. This application is based on finding equipment that e.g. hasfulfilled a certain purpose and there is an interest for re-collectingthe equipment due to e.g. economical or environmental purposes. Anotherexample in addition to the above-mentioned is e.g. a test torpedo shotfrom a submarine. The test torpedo is easily located by means of thelocation signaling device according to the invention, when it hasstopped and shall be picked-up for re-use.

A further application is to signal the location of equipment which hasbroken down, has crashed or which has been damaged on its travel.Therefore the position is unknown and most often the object is lost. Bymeans of the location signaling device according to the invention, theposition is easily detectable.

Yet another application is to mark a certain location. For instance, thelocation signaling device according to the invention may be dropped froma fixed wing or rotary wings aircraft that has located a certain objector person. The location signaling device is then dropped at the positionand inflates the wing balloon, thus signaling this location. The objector person may then be easily located and picked up from e.g. a vessel ora motor vehicle, or a fixed wing or rotary wings aircraft depending onthe nature of the location. The present invention has been describedabove with reference to specific embodiments. However, other embodimentsthan the preferred above are equally possible within the scope of theappended claims, e.g. different wing shapes than those described above,etc.

Furthermore, the term “comprises/comprising” when used in thisspecification does not exclude other elements or steps, the terms “a”and “an” do not exclude a plurality and a single processor or otherunits may fulfill the functions of several of the units or circuitsrecited in the claims.

What is claimed is:
 1. A signaling device for signaling a location, saiddevice comprising an airfoil fixed to a first end of a tether linewherein: said airfoil comprises an aerodynamically shaped body having awing attack surface configured for generating a lifting force in airflowing relative to said airfoil; said airfoil comprises a flexible wingportion, whereby said attack surface of said airfoil is passivelyreduced by an increase in air flowing relative to said airfoil; and saidflexible wing portion is arranged such that increasing relative air-flowpassively decreases a lift generating surface of said airfoil.
 2. Thesignaling device of claim 1, wherein said aerodynamically shaped body isarrow-shaped.
 3. The signaling device of claim 1, wherein said airfoilconsists of a single flexible wing portion.
 4. The signaling device ofclaim 1, wherein said airfoil comprises two flexible wing portions. 5.The signaling device of claim 1, wherein said airfoil comprises aninflatable, aerodynamically shaped hollow body.
 6. The signaling deviceof claim 5, wherein said device further comprises a housing configuredfor enclosing said airfoil and tether line when said inflatable,aerodynamically shaped hollow body is not inflated.
 7. The signalingdevice of claim 6, wherein said device further comprises a gas storagedevice containing a stored gas and configured to inflate saidinflatable, aerodynamically shaped hollow body.
 8. The signaling deviceof claim 7, wherein said stored gas is a lighter-than-air gas.
 9. Thesignaling device of claim 7, wherein said device further comprises aflow limiting valve configured for controlling a rate at which saidstored gas inflates said inflatable, aerodynamically shaped hollow body.10. The signaling device according to claim 1, wherein said airfoilcomprising at least one radar reflecting surface.
 11. The signalingdevice according to claim 1, wherein said airfoil comprises a radarreflective tail attached to said airfoil.
 12. The signaling deviceaccording to claim 1, wherein said airfoil has a highly visible color.13. The signaling device according to claim 1, wherein said airfoilfurther comprises a smoke generating means.
 14. The signaling deviceaccording to claim 1, wherein said airfoil further comprises a chemicalheat generating means.
 15. The signaling device according to claim 1,wherein said flexible wing portion is configured to limit a loadproduced by said lift generating surface of said airfoil on said tetherline when a second end of said tether line is fixed to said location andsaid airfoil is aloft.
 16. The signaling device according to claim 1,wherein said airfoil is configured for converting relative airflow to areciprocating, waving, elliptical, or figure 8 motion of said airfoil.17. A method of generally keeping static a dragging force on a tetherline connected to an airfoil aloft in an airflow, said airfoilcomprising a flexible wing portion, said method comprising: passivelyvarying a wing attack surface of said flexible wing portion by saidairflow, such that increasing airflow passively decreases a liftgenerating surface of said flexible wing portion.
 18. The method ofclaim 17, wherein said airfoil comprises an inflatable, aerodynamicallyshaped hollow body and said method further comprises inflating theinflatable, aerodynamically shaped hollow body and thereby forming saidairfoil.
 19. The method of claim 17, wherein the flexible wing portionbends in response to an increasing velocity of airflow, and therebydecreases the lift generating surface of the airfoil.
 20. The method ofclaim 17, wherein the lift generating surface of the flexible wingportion is decreased as a result of an inward movement of the flexiblewing portion in response to an increasing air velocity with respect tothe airfoil.